1. Field of the Invention
The invention relates in general to an adjustable lens module, and more particularly to an adjustable lens module and an image projector applied with the same.
2. Description of the Related Art
Along with a higher living standard is desired, home theater is gaining a wider and wider popularity. The image projector used in a home theater, such as a back projection TV for instance, is now experiencing a fierce competition. Therefore, how to produce an image projector to meet the consumer's high expectation of quality has become an imminent challenge to the manufacturers.
An image projector mainly includes a light source, an optical assembly, an imaging device and a lens module. The image projector functions by enabling the beam of light generated by the lamp to be projected to the imaging device via optical assembly, and then the beam of light is further reflected to the lens to generate an image. The optical assembly includes a color wheel, a condenser and a fold mirror. Examples of the imaging device include a digital micro-mirror device (DMD) and a liquid crystal display (LCD) panel. When the image projector functions, the optical path from the lamp to the imaging device has to be corrected, so that the luminance region generated when the beam of light is projected to the imaging device overlaps with the imaging device, enabling the image of the imaging device to be completely projected onto a screen via a lens of the lens module. If the lamp is erroneously positioned, the problems such as weakened brightness, poor imaging quality and evenness in distribution would arise.
Typically, there is no adjustable apparatus installed in the typical image projector for adjusting the illumination system. Normally, the lamp sleeve in which the lamp is mounted is directly mounted on the housing. For example, a positioning piece situated at one end of the lamp sleeve is secured at the housing via a screw. Once assembled, the components can no longer be adjusted. If the lamp sleeve is made of expensive materials, the manufacturing cost can not be decreased if the yield rate is low. Also, it is diffucult to optimizing the optical quality of the image projector and lack of flexibility of assembly without the adjustable lamp. Neither the single-lamp, nor the dual-lamp and nor the multi-lamp system is capable of optimizing the optical quality by adjusting the imaging system of the tube. The lamp has to be adjusted as well. According to the conventional method of mounting the lamp on the housing, the adjustment method is inflexible and the optimization of image projector is hard to achieve.